/// <summary>

    /// MD5加密解密帮助类     /// </summary>     public static class DESHelper     {         /// <summary>         /// MD5加密         /// </summary>         /// <param name="pToEncrypt"></param>         /// <param name="sKey">密钥(8位字符)</param>         /// <returns></returns>         public static string MD5Encrypt(string pToEncrypt, string sKey)         {             DESCryptoServiceProvider des = new DESCryptoServiceProvider();             byte[] inputByteArray = Encoding.Default.GetBytes(pToEncrypt);             des.Key = ASCIIEncoding.ASCII.GetBytes(sKey);             des.IV = ASCIIEncoding.ASCII.GetBytes(sKey);             MemoryStream ms = new MemoryStream();             CryptoStream cs = new CryptoStream(ms, des.CreateEncryptor(), CryptoStreamMode.Write);             cs.Write(inputByteArray, 0, inputByteArray.Length);             cs.FlushFinalBlock();             StringBuilder ret = new StringBuilder();             foreach (byte b in ms.ToArray())             {                 ret.AppendFormat("{0:X2}", b);             }             ret.ToString();             return ret.ToString();         }         /// <summary>         /// MD5解密         /// </summary>         /// <param name="pToDecrypt"></param>         /// <param name="sKey">密钥(8位字符)</param>         /// <returns></returns>         public static string MD5Decrypt(string pToDecrypt, string sKey)         {             DESCryptoServiceProvider des = new DESCryptoServiceProvider();             byte[] inputByteArray = new byte[pToDecrypt.Length / 2];             for (int x = 0; x < pToDecrypt.Length / 2; x++)             {                 int i = (Convert.ToInt32(pToDecrypt.Substring(x * 2, 2), 16));                 inputByteArray[x] = (byte)i;             }             des.Key = ASCIIEncoding.ASCII.GetBytes(sKey);             des.IV = ASCIIEncoding.ASCII.GetBytes(sKey);             MemoryStream ms = new MemoryStream();             CryptoStream cs = new CryptoStream(ms, des.CreateDecryptor(), CryptoStreamMode.Write);             cs.Write(inputByteArray, 0, inputByteArray.Length);             cs.FlushFinalBlock();             StringBuilder ret = new StringBuilder();             return System.Text.Encoding.Default.GetString(ms.ToArray());         }         /// <summary>         /// 获取Key         /// </summary>         /// <returns></returns>         public static string GetKey()         {             return "wanghuai";         }     }